StumpOS/STUMPOS.s at master · HarryFoster1812/StumpOS · GitHub

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#include "macro_def.c"

; ====================================================
;  STUMP OS – DEMO ENVIRONMENT FOR COMP22111 STUMP
; ====================================================
ORG &0000
bal boot

sys_call_function defw sys_call
sys_table_pointer defw SYSCALL_TABLE
return defw return_func
kernel_pcb_pointer defw kernel_pcb
kernel_stack_pointer defw kernel_stack_base

peripheral_table_pointer DEFW PERIPHERAL_TABLE
util_table_pointer DEFW util_table
pcb_head defw 0x0

kernel_statistics_table_ptr DEFW kernel_statistics_table

stack_size defw 0x50

current_pcb DEFW 0x0 ; this is the address of the pcb that is curerntly running
HEAP_START_POINTER DEFW HEAP_START
HEAP_END_POINTER DEFW HEAP_END
program_table_ptr_main DEFW program_table
org 0xE
panic:
J_SYS_CALL(panic_func)

; NOTE: The very first sys_call should be sys_enter otherwise the context switching
; will have undefined behaviour

; ---------------------------
; boot / reset initialization
; ---------------------------

boot:
    ; -----------------------
    ; 1) zero PCB bookkeeping
    ; -----------------------
    st r0, [ r0, #pcb_head ]     ; pcb_head = 0
    st r0, [ r0, #current_pcb ]  ; current_pcb = 0

    ; -----------------------
    ; 2) init heap pointers & header
    ; -----------------------
    ld r2, [ r0, #HEAP_START_POINTER ]   ; r2 = HEAP_START (address)
    ld r3, [ r0, #HEAP_END_POINTER ]     ; r3 = HEAP_END (address)

    sub r1, r3, r2
    sub r1, r1, #block_header_struct_size  ; r1 = payload size available (u16)

    ; store size in header: [r2 + 0] = r1
    st r1, [ r2, #block_header_size_offset ]

    ; store is_free = 1 : [r2 + 1] = 1
    mov r4, #1
    st r4, [ r2, #block_header_is_free_offset ]

    ; store owner
    st r0, [ r2, #block_header_owner_offset ]

    ; -----------------------
    ; 3) init kernel PCB & kernel stack
    ; -----------------------
    ; kernel_pcb layout:  offset 0 = kernel_stack_top, offset 1 = is_sys_state (based on uses)
    ; set kernel_stack_top = kernel_stack_end, clear is_sys_state (0)

    ld r5, [ r0, #kernel_stack_pointer ] ; r5 = kernel_stack_end (symbol word)
    ld r4, [ r0, #kernel_pcb_pointer ]
    st r5, [ r4, r0 ]            ; kernel_pcb->r6 = kernel_stack_top

    mov r6, #0
    st r6, [ r4, #1 ]        ; kernel_pcb->is_sys_state = 0

    ; set runtime r6 (SP) to kernel stack top so kernel runs with proper stack
    mov r6, r5                       ; set r6 = kernel_stack_end

    ; -----------------------
    ; 4) clear peripherals / visual reset
    ; -----------------------
    ; call clearLCD and clearLED to make a predictable starting screen


      add r5, r7, #6
      PUSH(r5)
      ld r5, [ r0, #sys_table_pointer ]
      add r5, r5, #15
      add r5, r5, #15
      ld r7, [ r5, #reset_peripherals_func]

    ; -----------------------
    ; 5) clear kernel statistics
    ; -----------------------
    ld r1, [r0, #kernel_statistics_table_ptr]
    st r0, [r1, #pcb_count_offset]
    st r0, [r1, #syscall_count_offset]
    st r0, [r1, #memory_allocated_words_offset]
    st r0, [r1, #system_ticks_offset]


    ; sys_enter
    ld r1, boot_proc
    add r4, r0, #enter_func
    SYSCALL()

boot_proc defw boot_user

return_func:
POP(r7)

#include "./User/user_program_table.s"

#include "./util/util.s"


#include "./Scheduler/PCB_controller.s"
#include "./kernel_data.s"
#include "./kernel_statistics.s"
#include "./Scheduler/context_switch.s"
#include "./Scheduler/yield.s"
#include "./Syscalls/panic.s"
#include "./Heap/heap_alloc.s"

#include "./Peripherals/peripherals.s"


#include "./Heap/heap.s"